Recently, the increased sensitivity of the market to environmental issues led car makers to spend efforts in developing hybrid vehicles and electric power vehicles having an electric engine to drive the wheels.
Power density of electric engines is such that it is possible to design a motor radially mounted within the rim of the wheel in all or some of the wheels of the vehicle, thus defining respective motor wheel assemblies.
Normally, a braking device, either a caliper or a shoe brake, is mounted within the radial dimension of the rim. Therefore, a design problem rises how to configure the electric motor and the braking device for the new vehicles.
In a known proposed solution to this problem, the electric motor is radially housed within the rim and the braking element is a shoe brake is concentric with the electric motor. Such solution requires the design from scratch of the braking element and is not suitable for retrofitting an already existing vehicle. In case of a restyling of the vehicle, the eventual redesign of the braking element would also require a new homologation procedure and is therefore costly.
In another solution, the braking element is eliminated and the electric motor is used to brake the vehicle. Also in this case the braking system shall be redesigned and the vehicle homologated again.